A pseudo differential complex filter for Bluetooth with frequency tuning

A 12th-order OTA-C complex filter with a nonconventional frequency tuning for a Bluetooth receiver is implemented in a low-cost mainstream 0.35-μm CMOS process. This proposed frequency tuning scheme is simpler than the conventional one based on phased-locked loop (PLL). Furthermore, a high-speed pseudo differential OTA using common-mode feedforward (CMFF) and common-mode feedback (CMFB) strategy is proposed. The filter bandwidth is 1 MHz and is centered at 2 MHz. Image and adjacent channels are attenuated by more than 45 and 27 dB, respectively. The integrated input referred noise is 29 μV_rms, and the filter chip dissipates 4.7 mA from a 2.7 V supply. The theoretical and experimental results are in good agreement.